S p e c i a l r e p o r t
'Golden' menace in Ifugao rice terraces
B y
K.T. Dancel1 and R.C. Joshi2
1Office of the Deputy Executive Director for R&D 2Crop Protection Division
P hilippine R ice R esearch In stitute M aligaya , M uñ oz, 3 110 N u eva E cija
P hilippines
A fe m a le g o ld en apple s n a il can lay a b o u t 25- 3 2 0 stra w b erry p in k eggs a t one time. These eggs m ature in a b o u t 10-1 5 days
EDITOR'S NOTE
You may well ask why a rice paper in an aquaculture newsletter? "We need a new solution to the old golden apple snail prob
lem, and an integrated approach with fishfarming may be the answer," explains Dr. Ravindra Joshi, a PhilRice research fellow, when he visited SEAFDEC/AQD on January 25. Me presents this problem in the hope that researchers on aquaculture may become interested enough to work with him. Dr. Joshi can be reached at:
<[email protected]> or <joshiravi
@hotmail.com> Telefax (63-02) 843 5122 If the golden apple snail (GAS) were real
"gold", farmers in the Ifugao Rice Terraces (IRT) would have been grateful to those who brought it to the world-renowned spot in the Philippines.
Now one of the major rice pests in the IRT, GAS has been significantly reducing the current yield of about 1.34 tons per ha annually, which is barely enough to feed the families for the whole year.
Scientifically known as Pomacea canaliculata (Lamarck 1822), GAS has been known in the Philippines to habituate only the lowland areas and its reproduc
tion is limited by low temperature, high el
evation, and salinity. Surprisingly, a group led by Dr. Ravindra Joshi, a crop protec
tion specialist at the Department of Agri
culture-Philippine Rice Research Institute (DA-PhilRice) discovered that GAS can survive in cool, elevated areas as demon
strated by a large number of GAS in the IRT, which is 4,000-5,000 ft above sea level.
Unaware of the possible threats posed by GAS, rural folks in the IRT brought it from the lowland areas for human and ani
mal consumption and for weed control.
Rice seedlings raised in the lowland areas, which could have borne eggs or hatchlings, were also transplanted in the IRT particu
larly in the upper terraces. GAS was spread all over the IRT through the terrace irriga
tion system.
The International Rice Research Insti
tute (IRRI) library website (http://www.
ricelib.irri.cgiar.org) shows some 65 refer
ences indicating that GAS research has been concentrated in the lowland areas. As a result, most of the control measures es
tablished cannot be applied in the IRT be
cause of its unique characteristics. Current GAS research in cool, elevated areas looks at possible control measures such as the use of indigenous plants as attractants, search
fo r natural predators, modification of wa
ter management techniques, development of crop protection practices that can be timed to increase GAS mortality, and dis
covery of more palatable food recipes for human and animal consumption.
Tracing the origin
Earlier studies conducted by researchers from the University of the Philippines at Los Banos (UPLB) and DA-PhilRice claim that GAS was introduced in the Philippines between 1982 and 1984 from Taiwan, Florida, and Argentina as food and protein source of Filipino farmers. Because of this, GAS was massively cultured and distrib
uted in different lowland areas of the coun
try and now has become one of the major pest problems in rice production.
In Argentina. GAS is not a problem according to Dr. Nestor Cazzaniga of the Universidad Nacional del Sur Departmento de Biologia. Although rice is not a staple food in Argentina, large portions of lands are planted to rice because it is exported.
Because its production is highly mecha
nized, fields are properly leveled and wa
ter is well-managed and controlled, mak
ing it less prone to GAS infestation.
The first report on GAS infestation in the Philippines came out in 1986 when about 300 ha of irrigated lowland rice fields in Region 2 were heavily damaged. In the same year, farmers in the IRT started to notice the same. By 1988, GAS has already damaged about 4% of the country's total rice area and in 1990, the damage reached
11%.
GAS invasion in neighboring countries
A study conducted by Drs. Yoichi Yusa and Takashi Wada of the Kyushu National Ag
ricultural Experiment Station shows that the next page
golden kuhol menace by dancel & joshi
introduction and culture of GAS in Japan started as early as 1964 when a company introduced it as an aquarium pet. It became popular as food in the early 1980s but the production later declined because people did not like the taste of the snail. It was later disposed into rivers, ponds, creeks, and paddies. Damage to rice was reported in 1984 and in the same year, GAS was de
clared as a quarantine pest by the Ministry of Agriculture, Forestry and Fisheries. Still, aquarium shops in Japan continued to im
port and sell apple snails as pets. Natural predators currently used include the water birds, fish, turtles, fireworm larvae, and crabs.
In Thailand, it was introduced in 1982 from Japan and Taiwan. Mainly used as decoration in aquariums, GAS rapidly mul
tiplied and eventually produced excess stocks, which were thrown away and reached canals and rivers. The first GAS outbreak was recorded in 1988 south of Bangkok. Several indigenous plants that have been used to control it include the golden dewdrop (Duranta repens), mafia nok kum (A mmannia bacifera), pla khum dee kwai, and soapberry tree (Sapindus semarginatus).
In Vietnam, it was introduced in 1988 from South America and declared as a quar
antine pest in 1993. By 1997, it has already spread to 7 out of the 61 provinces. In Nghe
an province, an experiment on the use of fishes such as black amur and tilapia in controlling GAS shows considerable reduc
tion in GAS density to as high as 84% from summer to autumn and 64% from winter to spring.
It was only in 1990 that GAS was first detected in a household tank in Malaysia.
Its origin was unknown. Based on the size, it was concluded that GAS had been there for some three to four years earlier. The disperson of GAS in Malaysia was rela
tively slow because of the coordinated ef
forts of relevant authorities. Upon discov
ery of the GAS, the Department of Agri
culture formed the GAS Task Force at the national level. Small working committees were also formed at the district level to monitor the status of infestation and results of control measures employed. In selected areas, effective control measures include the use of salt water, pesticides, snail metal traps, and natural predators such as ducks.
An on-going trial on the integration of fish in rice culture has reported promising re
sults.
A year later after GAS was discovered in Malaysia, Pomacea sp. was found in a farmer's fishpond in Lao PDR. GAS started to invade neighboring fields when heavy rains flooded the pond causing it to over- fl ow. It was in 1993, when it damaged about 5 ha o f rice that it was brought to the atten
tion of the government.
In 1991, it was introduced in Cambo
dia through refugees who returned from Thailand. Farmers in Takeo intentionally raised it in their fields as food, just as they normally did with the native snails (Pila sp.). Since the native snails do not damage rice, farmers assumed the same for the GAS. One of the most popular attractants used is the dragon bone plant, which is re
ported to contain toxins.
In Australia, the software package CLIMEX was used in matching the cli
mates of geographical regions where P.
canaliculata is known to occur with that of other regions in the world. The match
ing showed that large regions within India.
China, and Australia are at risk for future GAS invasion.
Control methods
The GAS are most often found in moist soils with vegetation, commonly in rice paddies. They appear to be very still as they tightly stick to the stems of rice plants and burrow into the clayey soil when soil mois
ture declines. Their clustered pinkish eggs remain pasted on leaves and stems. Tiny and fragile as they appear, the GAS have high survival rates. An experiment con
ducted by the group of Joshi demonstrates that GAS can still survive during fallow
page 31 H a n d p ic k in g is s till o n e o f the m o st p ra c tic a l m eth o d s in co ntrolling
th e g o ld e n a p p le sn a il p o p u la tio n
The g o ld en a p p le s n a il can dam age new ly p la n te d rice seed lin g s o v e rn ig h t
12 SEAFDEC Asian Aquaculture Vol. XXII No. 1 January-February 2000
role of vitamins ... from page 10
The safety level of vitamin E has to be determined before administration (Waagbo 1994). According to Pulsford e t al. (1995), the phag o cy tic ac tiv ity o f kidney macrophages in flat fishes were enhanced when the fishes were fed higher amounts of vitamin E.
Conclusion
Still no clear conclusions can be drawn with respect to vitamin nutrition and fish immu
nity. So, attention should be given to im
prove the earlier recommended levels for different vitamins.
• Testing with different immune functions must include the mechanism by which a single nutrient accelerates different biological functions
• Safety levels of different vitamins must be determined before administration
• For antioxidant vitamins, care should be taken to avoid losses due to atmospheric oxidation and water leaching by using the recommended type such as phos
phate esters of ascorbic acid
• More work is needed for vitamins C and E supplementation beyond minimum di
etary requirements to clarify the benefits to fish health. So, metabolism of nutri
tional C and E forms needs further in
vestigative biochemistry
COMPLETE LITERATURE CITATION MAY BE REQUESTED FROM THE CORRESPONDING AUTHOR
golden apple snail ... from page 12
periods and possibly even during the dry period, as these burrow deep into the soil.
A female GAS can lay 25-320 eggs at one time. Incubation ranges from 10 to 15 days, and, depending on the temperature of the microenvironment, GAS normally lives from two to three years. The GAS do not feed only on rice. They also damage many cultivated and non-cultivated plants such a lotus (Nelumbo nucifera), taro (Colocasia esculenta), duckweed (Lenna minor L.), swamp cabbage (Ipomoea aquaica), mat rush (Juncus decipiens), wa
ter chestnut (Trapa bicornis), and water fern (Azolla spp.). It has a wide range of possible hosts and food substrate such as commercial livestock feeds, decaying mat
ter, animal flesh, and other important crops.
Because of this, GAS is difficult to con
trol. Compounding this problem is the oc
currence of heavy rains and the application of pesticides that kill a large number of beneficial organisms, particularly in and around the rice ecosystem.
TABLE 1 Volume of molluscicides purchased, 1980-1998, Philippines
YEAR VOLUME
(kg per ha)
1998 67,340
1997 241,683
1996 130.000
1992 180
1991 159
1990 0
1989 25
1988 64
1987 9
1986 6
1985 3
1984 3
1983 0
1982 0
1981 0
1980 0
Note: D oes not include 1993-1995 data Source: F ertilizer a n d Pesticide Authority, 1999
Molluscicides have been widely used to control GAS but these can also kill non
pest snails and other beneficial organisms.
From 1980 to 1988, the volume of mollus
cicides purchased increased (Table 1). The biggest volume recorded was in 1997, when about 241,683 kg per ha were purchased.
The country has already spent about US$23 m illion from 1980 to 1998 for molluscicides (Fig. 1).
The Strategic Extension Campaign launched in 1989 by the Food and Agricul
ture Organization (FAO) of the United Na
tions, Visayas State College of Agriculture (VISCA), International Rice Research In
stitute (IRRI) and DA-PhilRice introduced non-chemical methods such as pasturing ducks in rice field s a fte r harvest, handpicking, destroying egg clusters before final harrowing, transplanting older seed
lings, and installation of screens in water inlets. These practices however, remain untested in the rainfed, direct-seeded, and
page
golden apple snail ... fr previous page
hybrid rice production environments.
Joshi's team is currently conducting intensive GAS research focusing on life ta
ble analysis, off-season survival strategies, and crop compensation. According to Joshi, knowledge on the biology of the GAS can lead us to discovering more effective con
trol measures. He also said that current con
trol measures are not very effective if not done at the community level.
GAS study at DA-PhilRice
Studies conducted by DA-PhilRice aimed to establish the effectiveness of basal ap
plication in the reduction of GAS popula
tion and (he relation of GAS shell length to rice seedling damage. Results showed that GAS with shell length of 40 mm are most destructive to rice seedlings, while GAS with shell length of 5 mm and below were not capable of destroying rice seedlings (Fig. 2). Another study documented the cur
rent status of GAS infestation in the IRT.
The study was conducted in collaboration with the local government units (LGU) of the municipalities of Banaue, Mayoyao, and Hungduan and with DA, Lagawe, Ilugao. The study focused on the extent of damage and distribution; and knowledge and current control practices applied by farmers. Majority of farmers in the lowland areas uses m olluscicides, while others chose to handpick the GAS and pasture ducks in the fields. In the IRT, farmers use indigenous plants and decaying weeds as attractants, the most popular of which is the trumpet flower.
Prospects for further research
A more intensive study on the biology of the GAS is needed to develop more effec
tive control measures. One possible solu
tion is the use of indigenous plants as at
tractants. In the lowland areas, farmers use kangkong (Ipomea aquatica), sweet potato (Ipomea batatas), and papaya (Carica pa
paya) as attractants.
Another promising method is integrat
ing fish in the rice culture. Fish is integrated
in rice culture because of a number of ad
vantages such as controlling pests, increas
ing cash and non-cash income and the nu
tritional intake of farm households. A study conducted b y ICLARM in 1996 a t Quirino province showed that there is potential for rice-fish culture in upland areas.
The least explored area of GAS re
search in the Philippines is the use of aquatic predators such as fish, frogs, toads, and other water-borne organisms. Dr.
Matthias Halwart of FAO, Rome says that the common carp, Cyprinus carpio and Oreochromis niloticus can be used in con
trolling the juvenile stage of GAS. In Tai
wan, more than a million fingerlings of the
C. carpio and Mylopharyngodon piceus were released to control GAS. However, it is also very important to assess the safety of plants with molluscicidal activity against fishes that feed on GAS.
REFERENCES
Adalla CB and Rejesus BM. 1989. The golden apple snail, Pomacea sp.: A serious pest of lowland rice in the Philippines. In: I Henderson (ed). Slugs and Snails in the World, p 417- 422. Thorton Heath: British Crop Protection Council
next page FIG 1 Total amount spent for golden apple snail control using molluscicides, 1980-1998,
Philippines (from FPA 1999)
FIG 2 The effect of different golden apple snail sizes on rice seedling damage. Bars sharing the same letters are not significantly different (P<0.05) according to Duncan’s Multiple Range Test (DMRT)
32 SEAFDEC Asian Aquaculture Vol. XXII No. 1 January-February 2000
Ali J Bidin, Z Romli Zulkifli and Sin T. 1998, Pomacea sp. in rice fields: Malaysian experi
ences. Paper presented at the Interntl Work
shop on Integrated Management of Golden Apple Snail in Rice Production. 4-6 Aug 1998, Nghe an, Vietnam
Anonymous. 1998. Use of fishes in controlling golden snail in Nghe an Province. Paper pre
sented at the Interntl Workshop on Integrated Management of Golden Apple Snail in Rice Production. 4-6 Aug 1998, Nghe an, Vietnam Baker GH. 1998. The golden apple snail, Pomacea canaliculata (Lamarck) (Mollusca:
Ampulla-riidae), a potential invader of fresh
water habitats in Australia. Paper presented at the Sixth Australasian Applied Entomologi
cal Research Conference, The University of Queensland, Brisbane, Australia, 29 Sept - 02 Oct 1998
Chanyapate C. 1998. The golden apple snail problem in Thailand. Paper presented at the Interntl Workshop on Integrated Management of Golden Apple Snail in Rice Production. 4- 6 Aug 1998, Nghe an, Vietnam
Dong L. 1998. Golden apple snail and prelimi
nary study on its control in Vietnam. Paper presented at the Interntl Workshop on Inte
grated Management of Golden Apple Snail in Rice Production. 4-6 Aug 1998, Nghe an Vietnam
Halwart M I. 1994. The golden apple snail Pomacea canaliculata in Asian rice farming systems: present impact and future threat.
International Journal of Pest Management 40 (2): 199-206
Joshi RC, de la Cruz MS, Martin EC, Cabigat JC, Bahatan RF, Bahatan AD, Choy-Awon J, Chilagan NP, and Cayong AB. 1999. Current status of the golden apple snail in the Ifugao rice terraces, Philippines. Department of Ag
riculture-Philippine Rice Research Institute, Maligaya, Munoz, Nueva Ecija, 47 pp Phachomphonh B and Ketelaar J. 1998. Golden
apple snails in the Lao PDR. Paper presented at the Interntl Workshop on Integrated Man
agement of Golden Apple Snail in Rice Pro
duction. 4-6 Aug 1998, Nghe an, Vietnam Rejesus BM, Sayaboc AS and Joshi RC. 1988.
The distribution and control of the introduced golden snail (Pomacea sp.) in the Philippines.
Paper presented at the symposium on the Introduction of Germplasm and Plant Quar
antine Procedures, PLANTI. Gelanampong, Kuala Lumpur, M alaysia, 14-15 December 1988
Somony C. 1998. A short review of the golden apple snail in Cambodia. Paper presented at the Interntl Workshop on Integrated Manage
ment of Golden Apple Snail in Rice Produc
tion. 4-6 Aug 1998, Nghe an, Vietnam Yusa Y and Wada T. 1999. Impact of the intro
duction of apple snail and their Control in Ja
pan. The ICLARM Quarterly 22 (3): 9-13
###
catfish Phil ... from p 24
Summary
The catfish industry in the Philippines is budding and projected to expand in the coming years. This is evident from conver
sations with active catfish farmers who all hope to be able to expand production, whether backyard or commercial because their present production can hardly supply the demands of buyers.
NIFTDC a fisheries technology and development center in Dagupan City, how
ever, says that unless the government has a catfish program, expansion of the industry would be slow. Work on catfish research is only just starting and the culture methods remain to be on a gut feel basis. The farm
ers are left to survive on their own. Luck
ily for them, catfish is hardy, easy to grow, and has a growing market. Clearly, if cat
fish can provide cheap protein for more people, scientific support must be made available for the farmers.
P O S T S C R I P T
The Mangabol Lake (located between the provinces of Pangasinan and Tarlac) used to be the biggest source of catfish (native or hitong tagalog, C.
macrocephalus) in Luzon, perhaps even the Philippines (Philippine Fish
eries, 1952). An annual festival used to be held in the area, according to people in Bautista, Pangasinan. Fish
ers from all over Luzon would gather in Mangabol Lake, and on the day of the festival, a fog horn would sound and fishers simultaneously dive into the lake with their snare. The diver who got the biggest catch would win a prize (usually prestige). But the 1991 Mt. Pinatubo eruption overran the lake and Mangabol Lake remains to be unproductive until the present time.
Acknowledgement The writers thank the following for their kind assistance while gathering data: NIFTDC Officer-in-Charge Mr. Westly Rosario, Kathy, and Manang of NIFTDC, Ms. Soledad Cruz of the Bulacan Provincial Agriculture Office, Mr. Manuel Igharas of the Municipal Agriculture Office of Pandi, Bulacan, and Mr. Cesar Recio, Noel Bong Claudio, and Mang Nestor Lico of SEAFDEC Manila Office.
SEAFDEC protocol ... from p 19
running water and then placed inside the incubators. Incubators can be made of marine plywood or plastic basin with a flow-through water system and provided with aeration.
Pituitary glands can be dissected from the heads of sacrificed male catfish. Pitui
tary glands contain hormone(s) that can also be used to spawn the female catfish in sub
sequent runs.
Fertilization and hatching
Using the above procedure, fertilization rate can reach more than 90%, while hatching rate may range from 30 to 70%. When stripped, there are approximately 100 eggs per gram body weight of the female fish;
about 500 eggs are contained in one gram.
A female catfish has 20-25 g of stripped eggs on the average.
Hatchery and nursery rearing
Larvae can be maintained for four days in the same incubators without feeding. Cat
fish larvae are then transferred to bigger tanks and fed with newly hatched Artemia nauplii for three days and Moina for four days. Thereafter, larvae are given formu
lated feed of 150-200 microns size that con
tains 44% protein. Two week-old catfish fry can be sold to grow-out pond operators, who are advised to rear the fry in net cages suspended in either tanks or ponds. Or, the fry are reared further for 4-6 weeks in big
ger nursery tanks or ponds to reach 3-5 cm.
the appropriate size for stocking in grow- out ponds':
Packaging and transport
Catfish fry are counted and graded accord
ing to size, and then placed inside a plastic bag half-filled with water at 500 to 1000 fry per bag. The bag is thereafter oxygen
ated and tied. Native "bayong" bags may be used to hold the plastic bags in, when transporting a short distance only. When transporting by plane however, the plastic bags me better placed in styrofoam boxes with crushed ice filled to the brim.—NJD
